DECE^rBER, 1910. 



KNOWLEDGE. 



467 



When the new spectroheHograph is completely 

 installed, there is every reason to expect that 

 Professor Hale will surpass the results he has 

 already obtained. 



Figures 2 and 3 show 

 some of the Calcium 

 Flocculi photographed 

 with the Snow Telescope 

 and spectroheliograph. 



Further, the n e n\' 

 5-foot reflecting tele- 

 scope constructed b}- 

 Professor Ritchey was 

 thrown open for the dele- 

 gates to make observa- 

 tions. It was estimated 

 that stars down to the 

 17^ magnitude could be 

 visually observed, which 

 is half a magnitude 

 fainter than hitherto 

 approximately obtained, 

 whilst photographs show 

 stars down to the 21st 

 magnitude. 



Saturn formed the sub- 

 ject of much scrutiny, 

 and the definition, using 

 a magnification of 600. 

 was superb. S e \' e r a 1 

 important new features 

 on the planet were dis- 

 covered, whilst other de- 

 tails imperfectK' estab- 

 lished were confirmed 

 and full\- observed. 



Other objectsof interest 

 were viewed, such as the Cluster in Hercules, and it 

 is the good fortune of few astronomers to observe 



FlGC 



.A. 5 -foot Telescop< 



such objects with a magnifying power of 600, 



giving crisp definition and an aperture of five feet. 

 The 5-foot telescope can be arranged for visual 



work with an equivalent 

 focal length of 100-feet. 

 On the return journey 

 arrangements had been 

 made for the delegates to 

 visit the \arious observa- 

 tories of Lick, Univer- 

 sit\- of California at 

 Iierkeley, San Francisco. 

 Verkes, .Allegheny, and 

 Washington. Each of 

 these observatories placed 

 their instruments at the 

 disposal of the parties. 

 With such generosity and 

 among such a series of 

 powerful instruments it 

 would be invidious to 

 point to anv one in par- 

 ticular, bnt a striking 

 feature of the observa- 

 tions made with the 40- 

 inch telescope of the 

 Yerkes Observaton,' was 

 the ease with which one 

 could see the faintest 

 planetarv nebula and the 

 t\\o faint stars in the 

 King Nebula in Lyra. 



One cannot help feel- 

 ing that the science of 

 astronomy is very much 

 alive in .\merica. and 

 that such meetings not 



onlv stimulate the spirit of scientific research, but 



tend to national goodwill. 



kh 0. 



' at .Mount Wilson 



NoTi:. — In connection with the article printed on 



Professor Hale, who is now in England, has kindh 



Pages 433 



-5 in ■" Knowledge " for last month, 

 written the note which is jTrinted below. 



The article on the Mount Wilson Solar Observatory in tlie 

 November number of "Knowledge" contains so many 

 errors and obscure statements that it is impossible to correct 

 them all. The account of the Snow telescope is badly 

 confused. The concavity of the third mirror is not " very 

 great," as stated, but very slight, as the radius of curvature is 

 sixty feet. The light of the Sun, or other object under 

 observation, does not '" fall through " the two plane mirrors, 

 but is reflected from their silvered front surfaces. Nor do the 

 observers " stand round " the third mirror, but near the focal 

 plane, sixty feet from its face. " Pasadona " should be 

 ■'Pasadena," " Ellerton " should be "' Ellerman," and 

 '"Carnegie Institute" should be "Carnegie Institution" (the 

 Carnegie Institute is a combined library and museum in 

 Pittsburgh), 



Mr, Adams is second in charge, and serves as Acting 

 Director in the absence of the Director. Other members of 

 the staff, not mentioned in the article, are Professor Kapteyn, 

 Research .Associate : Professor Scares, Superintendent of the 

 Computing Division ; Dr. King, Superintendent of the Physical 

 Laboratory ; Professor Ritchey, observer with the sixty-inch 

 reflector ; Dr. St, John, solar observer ; Mr, Babcock and 



Dr. Foth, assistants, Mr. Backus has not been connected 

 with the Obser\'ator>' for several years. 



The description of photographs of the calcium lines (p. 435, 

 top of second column I is hopelessly confused, and the 

 subsequent remark, which seems to imply tha't " they can take 

 a photograph twice a day" in the physical laboratory, is 

 equally so. The meaning of "twenty-six acres below" (near 

 the foot of the page) is a mystery. The sentence "The 

 buildings are permanent, but others are still to come for the 

 great five-inch reflecting telescope " is diflficult to understand. 

 Apparently it refers to the sixty-inch reflecting telescope, 

 which has been in regular use in its dome since December, 

 190S, Possibly the author's visit to Mount Wilson was made 

 several years ago, as he does not mention the sixty-foot tower 

 telescope, erected in 1907, or the recently completed one 

 hundred and fifty foot tower telescope. 



The final sentence of the article is also misleading. The 

 Observatory did recei\e an appropriation of ^150,000 from 

 the Carnegie Institution for expenditure in one year, but less 

 than one-third of this was used for maintenance, the balance 

 being devoted to the purchase, construction and erection of 

 buildings and instruments. 



